1. By Caitlin Rae Principal supervisor: Assoc Prof Glenn Hyndes Co-supervisors: Dr. Michael Payne and Assoc Prof Thomas Schlacher

2. Background - Sandy beaches Sandy shores are dynamic transitional systems defining the boundary between sea and land. Exposed sandy beaches possess low in-situ production thus usually devoid of fauna. However, beaches can receive accumulations of detached seagrass and macroalgae (or wrack), which can often support various populations of consumers.

3. Background - Spatial subsidies Ecosystem boundaries are regularly crossed by materials, organisms and energy. Spatial subsidy = increase in production, food web structures and altered community dynamics in recipient ecosystems. From a high production donor to a low productivity recipient.

4. Ghost crabs (O.convexa) 5 species occur in Australia, all of which are in Western Australia. O.convexa is endemic to WA. Recognisable by its golden colour and lack of stylets on their eyestalks. Known to occur higher up the beach profile on drier slopes.

5. Significance and knowledge gaps Feeding and predation ecology of ghost crabs in Australia, in particular Western Australia’s endemic species – Ocypode convexa (Golden ghost crab). Interaction and effect of wrack accumulations on Ghost crab populations along the Western Australian coastline. Figure 1. O.convexa (Golden ghost crab). Source: Gnaraloo Turtle Conservation Program, 2010).

6. Aims Broad aim: Determine the interactions between the ghost crab Ocypode convexa (Golden ghost crab) and wrack on sandy beaches, and its role as a vector in transporting material from marine to terrestrial environments. Objectives: Determine if there is a correlation between ghost crab (Ocypode convexa) densities and wrack accumulations; Do they feed on wrack detritus or fauna associated with wrack and; Determine if they an important vector in transporting material from marine to terrestrial environments.

7. Research design Preliminary beach survey: To establish large populations of O.convexa for sound representation. Establish areas of wrack accumulation. Figure 2. Potential sampling locations in the mid-west region of Western Australia. Source: Google Earth.

8. Research design cont’d. Field investigation: Spatial study over 12 months. 3 or more locations will be selected, ranging from Perth to Geraldton. Feeding experiment: Determine what elements of the wrack O.convexa eat. Potential stomach content analysis and stable isotope analysis to determine those components which have been ingested and/or assimilated.

9. Summary Identify if ghost crab (O.convexa) abundances correlate to large accumulations of wrack. Determine diet of Ghost crabs (O.convexa) in regards to wrack. Do they transfer material from the marine to the terrestrial environment and to what effect.